We are studying the structures, biosynthesis, and functions of glycoproteins. Our systems include formal and transformed cells and a MOPC cell line secreting soluble and membrane-bound IgM. The transformants include malignant and non-malignant cells. The major cell surface change which gives the best correlation with tumorigenicity can be detected by two dimensional electrophoresis of glycoproteins or Sephadex chromatography of glycopeptides. We are conducting chemical studies on purified glycoproteins to determine the nature of the change. We have isolated a cell glycoprotein of 100,000 daltons which appears to be a cell membrane antigen involved in tumor regression. Immunogenic spontaneous transformants express the antigen, and normal cells appear to have a similar antigen which lacks carbohydrate. We are also conducting new studies on the structure and biosynthesis of IgM synthesized by MOPC 104E. The glycoprotein has six oligosaccharide side chains, including high mannose and complex type. We intend detailed in vivo and in vitro studies of glycoprotein biosynthesis, with particular interest in processing to high mannose and complex-type oligosaccharides. These experiments will include in vitro translation of IgM mRNA as a tool for characterizing the glycosylating complex.